Table 3 Summary of key modifications made to the PAD-C following each round of interviews

Training guide

Training guide sections were removed to reduce respondent burden

A new section was added to the Training Guide to reinforce that children should give the diary back to their parent/caregiver after completing the items, as this instruction was often missed by children within the diaries

Wording in the Training Guide was updated to reflect the possibility that diary answers could be shared with the doctor

Instructions

An instruction in the Morning Diary and Bedtime Diary explaining when to answer the questions was removed to reduce respondent burden and avoid repetition of the same information included in the Training Guide

There were no key modifications made to the PAD-C instructions following Round 2 child interviews

An instruction in the Bedtime Diary was updated to specify “bedtime” as the end of “today” more clearly

Core items

Item stems were updated for items assessing frequency of cough and wheeze to ensure phrasing consistency across the frequency items

Response options for the global nighttime asthma symptom severity item were updated to allow respondents to indicate that no symptoms were experienced to support future potential symptom-free days endpoints

The response scale for the item assessing cough intensity was updated to an alternative response scale tested in Round 2 interviews, following feedback from participants that they could have a frequent cough that is not severe

The definition of “wheezing” in the Training Guide was simplified and added to the item assessing wheezing to facilitate participant understanding

A definition of asthma symptoms included in the Training Guide was added to the global nighttime asthma symptom severity item as a separate sentence to facilitate participant understanding

One of the response options for the global nighttime asthma symptom severity item was updated to specify asthma symptoms, to reinforce the context of asthma and facilitate understanding

There were no key modifications made to the PAD-C core items following Round 3 child interviews

Supplementary items

Rescue inhaler items were updated to include a definition of rescue inhaler, in addition to child-friendly terms to improve participant understanding

New supplementary items assessing whether the child has a nebulizer were added to both diaries, as not all participants in Round 1 interviews reported having a nebulizer to use for asthma treatment. Similar to other existing items, instructions for skip logic were included and tested to ensure that when completed on an electronic device, those who do not have a nebulizer (i.e., those who select “No”) can skip the following nebulizer items to reduce respondent burden

Wording in the nebulizer items was updated to facilitate understanding; an alternative term for nebulizer was added

To reinforce the recall period and ensure accurate data collection, relevant recall periods were added to items assessing amount of rescue inhaler used and number of times nebulizer used. The response option and item wording were also updated to clarify that participants should report the total number of puffs or times used

A definition of rescue inhaler in the rescue inhaler items was refined and shortened and an alternative term for “rescue” was removed due to lack of understanding

The nebulizer items were updated to ensure that they collect data on rescue medication use only as some participants in Round 2 interviews stated that nebulizers were used for both rescue and maintenance medication

Due to lack of understanding in Round 3 interviews, a definition of rescue inhaler in the rescue inhaler items was updated to include wording that was previously tested and well understood in Round 2 interviews

Wording included in the nebulizer items specifying rescue medication use was simplified to similar wording that was tested and well understood in Round 2 interviews, to facilitate participant understanding

Developmental items

Response options for the global daytime asthma symptom severity item were updated to allow respondents to indicate that no symptoms were experienced to support assessment of change

A definition of asthma symptoms included in the Training Guide was added to the global daytime asthma symptom severity item as a separate sentence to facilitate participant understanding

One of the response options for the global daytime asthma symptom severity item was updated to specify asthma symptoms, to reinforce the context of asthma and facilitate understanding

There were no key modifications made to the child developmental items following Round 3 child interviews